Although gas and vapor are two terms that are typically used interchangeably, the term xe2x80x9cgasxe2x80x9d is normally used for substances that exist completely as gases in room temperature. An example of a gas is oxygen. The term xe2x80x9cvaporxe2x80x9d is more commonly used for substances that generally exist as a liquid or solid at room temperature, although certainly capable of being present in a gaseous phase. Vapor pressure is a physical property of specific materials and is normally measured at a standard temperature of 77xc2x0 Fahrenheit (25xc2x0 Celsius). Chemical liquids or other substances that have a vapor pressure greater than the surrounding atmospheric pressure will evaporate into the atmosphere as a vapor and then diffuse outwards until an equilibrium pressure and uniform concentration is reached. Normally, the diffusing vapor (or gas) will reach equilibrium sooner if the volume of the space into which the vapor diffuses is confined or otherwise limited, as in a container, room or beneath a foundation slab. When the available volume into which gases or vapors can diffuse is limited, the resulting vapor pressure and gaseous concentration may reach equilibrium with the evaporating solid or liquid parent material (liquid being the more common of the two types of parent material) and no more material will evaporate. In this situation, the material will exist side-by-side in two different phases. If the available volume into which a gas is diffusing is essentially unlimited, such as the atmosphere itself as found in an uncovered outdoors location, the material will continue to evaporate and diffuse until it is all in the vapor state and the gaseous concentrations are so low as to be difficult to detect. Materials that have a tendency to evaporate at standard temperature and pressure are said to be volatile. If the materials are also organic compounds, they are called volatile organic compounds (xe2x80x9cVOCsxe2x80x9d).
A nonlimiting example of a VOC is perchloroethylene (also known by an assortment of common other names including perc, perchloroethene, tetrachloroethylene, tetrachloroethene, and a variety of trade names), the most widely used chemical in the dry cleaning industry. Perc has a vapor pressure greater than the normal atmospheric pressure of 14.7 p.s.i. at standard temperature and therefore behaves as a VOC and will evaporate. As a liquid, perc has a low interfacial tension and viscosity and readily penetrates into and through typical concrete slab foundations. Once perc has penetrated through a concrete slab into the subsurface beneath, perc begins or continues to evaporate. The accumulating perc vapors do not normally have sufficient pressure to migrate back upwards through the concrete slab (although human exposure to indoor VOC vapors moving upwards through expansion joints, cracks and other penetrations in slabs can become a problem). More often, the perc vapors effectively become trapped below the concrete slab in the pore spaces within the soil. These perc vapors move laterally away from the source area, passing from pore space to pore space within the soil until the vapors become widely diffused in the subsurface beneath the concrete slab. The rate at which the VOC vapors accumulate and migrate depends on the amount of the liquid chemical that has been released, the organic content and the nature of the soil itself and the amount of fluid (normally water) that is also present in conjunction with the VOC or is already residing in the pore spaces.
It is important to detect VOC vapors as close to the source of the release as possible. A basic risk-based closure of facilities that have had a minimal impact or exposure to a VOC, e.g., perc, normally costs tens of thousands of dollars, even without the undertaking of any significant remediation or cleanup effort. Facilities that are significantly impacted, such as perhaps including ground water contamination, easily run into hundreds of thousands of dollars for remediation. This does not include the lost business opportunities, third party liability considerations and other miscellaneous damage claims.
There are a number of systems that monitor the VOC content of the air. Typically, these systems are expensive and difficult to maintain. If the subsurface impacted to the extent the VOC is in the aboveground air in a concentration that is capable of detection, the expense can already be overwhelming in terms of remediation and liability. Examples of this type of technology include that disclosed in U.S. Pat. No. 4,111,034, which issued on Sep. 5, 1978.
The present invention is directed to overcoming one or more of the problems set forth above.
In one aspect of the present invention, a vapor trap for detecting VOCs is disclosed. This system includes a housing, having a first end portion, a second end portion and at least one opening for receiving gas vapor, wherein the housing is at least partially buried in ground and a vapor containment or a vapor sampling mechanism is detachably connected in a fluid relationship to the first end portion of the housing.
In another aspect of the present invention, a method for detecting VOCs utilizing a vapor trap is disclosed. The method includes at least partially burying a housing in ground, wherein the housing includes a first end portion, a second end portion and at least one opening in the housing, wherein the first end portion of the housing is detachably connected in a fluid relationship to a vapor containment or sampling mechanism.
Yet another aspect of the present invention is that VOC releases can be detected before the costs for investigation and clean up become exorbitant.
Still another aspect of the present invention is that VOC releases can be detected before tenants are overwhelmed with inconvenience and expense, which can force the tenant to vacate the premises or property owners to evict the tenant.
Another aspect of the present invention is that VOC releases can be detected before contamination spreads to affect other tenants and property owners to create third party liability.
Yet another aspect of the present invention is that VOC releases can be detected while the contamination is restricted to soil since the contamination of ground water raises the remediation costs and complications significantly.
Another aspect of the present invention is that VOC measurements can be made by technicians without the need of highly specialized, environmental professionals.
Yet another aspect of the present invention is that obtaining VOC measurements on a predetermined basis will demonstrate to an insurance company that the land owner is pro-active about pollution and has the ability to minimize potential problems, which should result in reduced insurance premiums.
Still another aspect of the present invention is that obtaining VOC measurements on a predetermined basis will provide land owners with a mechanism for checking on the general housekeeping practices of a tenant to correct unsatisfactory work practices that can create additional spills and releases of VOCs as well as allowing the land owner to repair leaking equipment.
Another aspect of the present invention is that obtaining VOC measurements on a regular basis provides the tenant with a reminder that the landowner is very serious about preventing pollution.
Yet another aspect of the present invention is that obtaining VOC measurements on a predetermined basis provides evidence that may exonerate either the land owner or the tenant if accused of being a source of a VOC spill or keep either the land owner or the tenant from being falsely blamed as being the cause of unrelated contamination that is either located on-site or off-site.
In another aspect of the present invention is the quick (less than a day), low cost (less than half the price of a regular Phase 1 environmental site assessment) installation with minimal disruption and downtime that can be done with separate self-contained equipment that prevents electrical overload situations at the property where the invention is being installed.
Yet another aspect of the present invention is that very specific constituents in the vapor can be analyzed to minimize false alarms.
Still another aspect of the present invention is that installed vapor traps can be easily removed.
Another aspect of the present invention is that the monitoring of the vapor traps on a predetermined basis can be established through service contracts so that these costs can be budgeted as a regular operating expense.
These are merely some of the innumerable illustrative aspects of this present invention and should not be deemed an all-inclusive listing.